Gramophone



Nov. 21, 1933. c. YOSHIZAWA GRAMOPHONE Filed Aug. 4. 1930 2 Sheets-Sheet1 C .9 f. m

Nov. 21, 1933. c. YOSHIZAWA GRAMOPHONE Filed Aug. 4, 1930 2 Sheets-Sheet2 WWW 03h I avvk 6 3 M/veA/ToQ -nnw Patented Nov. 21, 1933 UNITED STATESPATENT OFFICE 1 Claim.

My invention relates to improvements in gramophones characterized in theprovision of a long and reversely curved sound channel or horncomprising partition walls vertically fixed between the top and bottomplates. The horn is made of plastic material such as gypsum,Portland-cement, hard rubber, celluloid, pulp, bituminous compounds,bakelite or any like plastic materials.

The object of the invention is to provide a gramophone producing a clearand undistorted sound closely similar to the original sound by avoidingharmful resonance and especially to reproduce low tone sounds distinctlyand accurately.

In gramophones the sound to reproduced is much influenced by the lengthof the sound channel, or so-called horn arranged between the sound tubeand the sound opening of the box. Gramophones provided with sound hornlocated outside the box may have a long sound way, but in gramophonesnot provided with trumpet it is difficult to provide a long andgradually widening sound channel within a lirn'ted box. The part of thehorn is thereby forr ed straight or only slightly curved toward theopening, forming a short sound channel so that the low pitched soundsare apt to be weak and indistinct.

According to the present invention a horn having a curved or scrolledsound channel of enough length is formed by curved partition wallsvertically fixed between the top and bottom plates. The manufacture ofthe horn is very simple and a sound tunnel of a rectangular section withthe desired length and gradually broadening L s sectional area towardthe outlet opening is obtained whereby a clear and unaffected sound maybe reproduced.

It is also noted that in gramophones hitherto known the part of thesound channel or the horn being made of metal or wood the propervibration of the horn itself aiiects the quality of the sound reproducedand the volume of the sound is changed from the original sound accordingto the nature of vibration and especially weakened for low pitchedsounds. Whereas, according to the present invention the horn being madeof plastic material comparatively free from vibration, the soundreproduced in the sound box is transmitted comparatively unchanged andthe sound closely similar to the original sound may be reproduced. Theplastic material may be moulded easily and being capable of increasingits thickness in proportion to the increase of the sectional areas thesound is further improved in this respect. The plastic material may bereenforced by suitable reenforcements.

The accompanying drawings show the improved gramophone embodying thepresent invention.

Fig. 1 is a vertical central sectional view of the gramophone.

Fig. 2 is a horizontal section thereof.

Fig. 3 is a cross sectional View of the horn removed.

Referring more particularly to the drawings the gramophone box (1) isprovided at the lower side of its top plate with a casing (2) withinwhich motor mechanism for driving the disk (3) is arranged. The soundbox (4) is fixed at the end of the elbow tube (5), the other end ofwhich is rotatably mounted on the sound tube (6) vertically leading intothe box (1) as usual.

The curved horn (11), which forms the essential feature of my inventionis formed by curved partition walls (10) vertically fixed between thetop plate (8) and the bottom plate (9) One end of said channel isconnected to the lower end of the vertical tube (6) and graduallyincreasing its sectional area toward the other end, opens at the outletopening ('7) formed at the front side of the box (1).

The horn is made of plastic material such as gypsum, Portland-cement,hard rubber, celluloid, pulp, bituminous compounds, bakelite or anyother similar materials. The top plate (8) and the bottom plate (9) ofthe horn are preferably made of said plastic materials, but they mayalso be made of Wood or metal in combination with the partition walls(10) of the plastic material.

The sound tube (6) is usually arranged at one side of the box (1) andfor convenience in connecting said tube, the horn channel is preferablycurved in one direction inwardly toward the centre and then from thecentre outwardly to the opening (7) the channel is curved in theopposite direction, as shown in Fig. 2. To gradually increase thesectional areas of the sound channel the distance between adjacentpartition walls (10) is gradually increased toward the outlet end of thehorn when the top plate (8) and the bottom plate (9) are parallel, asshown in Fig. 3. In case the partition walls are fixed at equal distancefrom one another, the top plate may be stepped for each compartment inplace of a single plate for increasing the sectional area of the soundchannel, and a plane bottom plate (9) is fixed at the bottom. A portionof the top plate 8 is inclined as shown in Fig. 1 to increase both thewidth and the height of the sound channel. The thickness of the walls ofthe horn, the partition posite ends in a sound inlet and a sound outlet,said partitions being arranged in spaced relation to each other andreversely curved to provide a. sound channel vortically wound in onedirection from the sound inlet to the centre of the horn and vorticallyWound in the opposite direction from the center to the sound outlet ofthe horn, said channel being rectangular in section and graduallyincreasing in area from the sound inlet to the sound outlet.

CHUZABURO YOSHIZAWA.

